In this type of device based on the prior art, a reel is rotatably mounted in a case and is energized in one direction by a spring, a rope is wound around this reel in the direction contrary to that in which the reel is energized, and a locking mechanism which stops the rope once wound around the reel and then dispenses it by a specified length at the specified position.
In the prior art devices as described above, however, if the rope is wound in too fast after locking is released, a metal fitting at an edge of the rope jumps, which may give an unexpected injury to the user. Thus the spring to energize the reel is made thinner and longer to make the reel's energizing force weaker (to a low torque) for damping the reel's speed to wind up the rope. In such a case, however, the winder does not work smoothly.
Several braking devices in the prior art have been directed toward the problem of rewinding the reel at safe speed without sacrificing recoil spring strength. For example, U.S. Pat. No. 4,500,048 to Schaller et al. discloses a one-piece bending centrifugal weight that is bent outwardly against a braking surface by rotation of a wheel inside the reel. That device has the disadvantage of being inherently complex and having substantial weight, distal to the point of rotation, not directly involved in the braking of the reel. Further, much of the centrifugal force of the brake is stored in the bending member of the brake, thereby damping the braking effect.
U.S. Pat. No. 4,907,756 to Bourrat is similar to Schaller. Though having two opposing weights as part of a centrifugal braking mechanism, those weights are contained immovably within a cradle pair, rendering in effect a bending centrifugal weight as disclosed by Schaller. Like the braking mechanism of Schaller, the braking mechanism of Bourrat has substantial weight not directly involved in the braking of the reel and inefficiently dampens, through the bending member, the braking mechanism.